Building protection system



1962 J. c. LESHER 3,051,934

BUILDING PROTECTION SYSTEM Filed Dec. 1, 1958 2 Sheets-Sheet 1 INVENTOR JOHN C LESHER ATTORNEYS 1962 J. c. LESHER 3,051,934

BUILDING PROTECTION SYSTEM Filed Dec. 1, 2 Sheets-Sheet 2 h /as MENTOR JOHN C L ESHER ATTORNEY S nite The present invention relates to building protection systems and more particularly to a remote control system employed to control the lights within a building from externally thereof. Still more particularly the invention provides a remotely controlled lighting system for buildings and other properties and a burglar alarm system which is integral therewith and also controls the lighting system of the building in response to illegal entry.

For many years it has been conventional for police to check periodically the premises of business establishments for prowlers and this had usually been accomplished by either a foot patrolman who shines a flashlight into the building or by policemen in prowl cars who direct the "spotlights on the prowl cars into the premises. The difficulty with this sort of procedure is that it is slow since the spot of light must be swept through the premises, that prowlers can very easily move out of the range of the spotlight or simply keep away from the beam, and that the policemen either on foot or in the prowl car who are performing the checking immediately warn the prowler of their presence and put him on his guard. Further, the spotlight on the prowl car or the flashlight in the hand of the policeman immediately tell the intruder where the policeman is and render him a ready target for the desperate criminal. Further difficulty with such systems is that even if a patrolman or policeman in a prowl car does spot an intruder in the building, as a result of the darkness of the premises, the intruder has a distinct advantage over the policeman while attempting to elude him since he can remain in shadowed areas and therefore remain substantially invisible.

The same difficulty that is experienced by policemen is encountered by night watchmen who are employed to protect particular premises since normally he has to patrol a substantially dark building and therefore is open to sudden and unforeseeable attack. Further, the procedure now employed renders the night Watchmans services only partially effective since again any prowler can elude a spotlight or, if lights are turned on in one room, he can usually move to another room which is still dark.

It is an important object of the present invention to provide an inspection system for utilization by policemen and night watchmen which permits all of the lights of a building or a substantial part thereof to be turned on by remote control from either intern-ally or externally of the building so that the entire building or premise is illuminated at the same instant.

It is still another object of the present invention to provide a remote transmitter unit which may be mounted in a police car or a portable trnasmitter unit which may be carried by a policeman and a receiver unit on the premises to be protected, which receiver is tuned to receive modulated carrier signals from the transmitter in order to control the lights within a building.

In accordance with the present invention a prowl car or patrolman is provided with a transmitter which transmits on a predetermined frequency and is modulated by a predetermined audio signal. The modulated carrier, which is transmittable at will from the transmitter, is received by a receiver disposed within a building to be protected. The receiver detects the modulating signal and then converts it into a direct current voltage which is employed to control a relay. The relay is employed tates tet "ice to control the lighting circuit of the building so as to turn on all or a substantial proportion of the lights of the building. Thus, a policeman walking down the street or passing the premises in a prowl car need merely throw a switch on his portable unit in order to completely illuminate a building.

A further feature of the invention is the provision of a burglar alarm system which is inter-related with the aforesaid receiver in order to turn on the lights within the premises whenever a burglar alarm system is actuated. The fact that the lighting system may be actuated by the burglar alarm increases the efficiency of the system since the police, upon arriving at the scene may immediately completely illuminate the building to facilitate a search for the criminal.

The unit mounted within the prowl car is provided with a carrier frequency selection system wherein one of the carrier frequencies is employed to control a remote receiver disposed within the building and the other carrier frequency may be employed to control trafiic lights along the route that a prowl car may follow in approaching a building from which a burglar alarm signal has been received. Thus, the single transmitter provided for the prowl car may serve a dual function with regard to traific light control as well as building light control.

The apparatus of the invention is not restricted to police use since firemen are often desirous of illuminating a building in order to determine the location and extent of a fire and the smoke hazard within the building. By being able to turn on all the lights in the building from the outside, firemen need not risk their lives in attempting to locate various light switches in order to evaluate the situation. The burglar alarm system may be replaced or utilized in conjunction with a fire alarm system which would affect the lighting system in the same manner as the burglar alarm system.

It is therefore another object of the present invention to provide a receiver for controlling the lights within a building which may be controlled by a transmitter located externally of the building or by means of burglar alarm systems located internally of the building.

It is a further object of the present invention to provide a transmitter for remotely controlling a light controlling receiver in a building which transmitter also may be employed to control trafiic lights along the route followed by an emergency vehicle.

It is another object of the present invention to provide a receiver unit which may control the lights of a building in response to remotely generated signals or which may respond to actuation of a burglar alarm in which latter instance a conductive loop of a burglar alarm is connected in the receiver circuit such that when the conductive loop is broken due to illegal entry the light control section of the aforesaid receiver is also energized to turn on the lights of the building.

The above and still further objects, features and advantages of the present invention will become apparent upon consideration of the following detailed description of one specific embodiment thereof, especially when taken in conjunction with the accompanying drawings, wherein:

FIGURE 1 of the accompanying drawings is a schematic wiring diagram of a first embodiment of a transmitter which may be employed with the system of the invention and which is intended to be mounted in a police prowl car or fire engine or similar vehicle;

FIGURE 2 is a schematic wiring diagram of a first embodiment of -a receiver which may be utilized as a unit of the system of the invention;

FIGURE 3 is a schematic wiring diagram of a burglar alarm system which may be incorporated in the system of FIGURE 2;

FIGURE 4 is a schematic wiring diagram of a second embodiment of the receiver which may be employed with the system of the invention; and

FIGURE 5 is a schematic wiring diagram of a portable transmitter unit which may be utilized with the system of the invention.

Referring now to FIGURE 1 of the accompanying drawings there is illustrated a transmitter unit which is adapted to be mounted in a motor vehicle such as a police car, the automobile or similar vehicle of a private detective agency or a fire engine or fire chiefs car.

The transmitter comprises a tetrode 1 having an anode 2, a screen grid 3, a control grid 4, and a cathode 5 connected tov a source of reference potential which is hereinafter referred to as ground. The tetrode 1 comprises an oscillator and a modulator tube and feeds an ant nna 6 of the system through an antenna transformer 7. The anode 2 of the tube 1 is connected to one end of a primary winding 8 of the antenna transformer 7 and the other end of the primary winding 8 is connected via a capacitor 9 to ground potential. The primary winding 8 is shunted by a variable capacitor 11 which is adapted to tune the resonant circuit comprising winding 8 and capacitor 11, to a predetermined frequency as will be explained subsequently. The antenna transformer 7 includes a secondary winding 12 having one end connected via a capacitor 13 to ground and having another end connected to the antenna 6. The secondary winding 12 of the transformer 7 and capacitor 13 constitute a broadly tuned series resonant circuit tuned approximately to the frequency of the parallel resonant circuit comprising winding 8 and capacitor 11.

The control grid 4 of the tube 1 is connected to one end of each of two piezo-electric crystals 15 and 16, the other ends of which are connected to fixed switch contacts 17 and 18 respectively. A movable switch contact 19 is adapted to engage selectively the contacts 17 and 18 and is connected via a coupling capacitor 21 to the screen grid 3. The switch comprising contacts 17, 18, and 19 is adapted to be actuated by an electro-magnet 23 having a coil 24 connected via a manual switch 26 to ground potential and having its other end connected to the battery of the vehicle in which the transmitter is positioned. The connection of the coil 24 to the vehicle battery may be through the ignition switch so that the system is inoperative when the ignition switch is turned off.

The grid 3 of tube 1 is connected through a high frequency choke 25 to a lead 26 and the lead 26 is connected through a primary winding 27 of a transformer 28 to a manual switch 2 9* which is employed to energize selectively the transmitter of FIGURE 1. The switch 29 is connected to a source of 13+ which may constitute a vibrator power supply of the appropriate voltage. The transformer 28 further comprises a secondary winding 31 having one terminal grounded and the other terminal connected to a grid 32 of a tri-ode 33 having an anode 34. connected to the lead 26 and a cathode 36 connected to ground. The grid 32 of the tube 33 is connected to ground through a capacitor 37 and a resistor 38. The tube 1 constitutes an element of a carrier frequency oscillator having its frequency controlled by the crystal 14' or crystal 16 depending upon which position the movable contact 19 assumes. The screen grid 3 constitutes the anode of the carrier oscillator with a portion of the signal energy developed across the choke 25 being fed back through coupling capacitor 21 to the circuit of the control grid 4. The signals fed back to the grid depend upon which of the crystals 14 or 16 is connected in the circuit and therefore the frequency of oscillation of the carrier oscillator is determined by the crystals.

In accordance with the invention, when the switch 26 is opened and the electro-magnet 23 is de-energized, the movable contact 19 engages the stationary contact 17 and the system is adapted to oscillate at a frequency for controlling lights internally of a building. When it is desired to control trafiic lights or other portions of a system, the switch 26 is closed in order to energize the electro-magnet 2'3 and cause the movable contact 19 to engage the stationary contact 18 to insert the crystal 16 in the grid circuit of the oscillator. The oscillations developed by the carrier oscillator are modulated by a predetermined audio frequency which for purposes of illustration may be taken to be cycles per second. The 115 cycle modulating signal is generated by an oscillator including the thiode 33 and the transformer 28 and the capacitor 37. The oscillator comprises a blocking oscillator which initially is conductive and feeds back energy through the transformer 28 in such a sense as to charge the capacitor 37 negatively until the grid 32 is driven to cut-off poten tial. Subsequently the capacitor 37 discharges through a resistor 38 and the tube is again rendered conductive with energy being fed back through the transformer 28' to increase conduction until the capacitor 37 is again charged sufiiciently negatively to prevent conduction through the tube. The 1 15 cycle per second signal appearing on the lead 26 is coupled through the coil 25 to the screen grid 3 of the tube 1. The carrier frequency signal generated by the oscillator comprising the elements 3, 4, and 5 of the tube 1 is modulated by the signal appearing on the grid 3 and therefore a modulated signal is applied to the tuned circuit comprising the primary winding 8 of the transformer 7 and the variable capacitor 11. The choke 25 prevents the RF. signals from appearing on lead 26 but allows the audio signals generated in tube 33 to be coupled to the grid 3. The antenna circuit is tuned by the capacitor 11 to a frequency mid-way between the natural frequencies of the crystals 14 and 16 so that either carrier frequency is passed with equal attenuations through the antenna circuit. Signals appearing across the primary winding 8 of the antenna transformer 7 are developed in the series resonant circuit comprising secondary winding 12 of a transformer 7 and the capacitor 13 therefore are applied to the antenna 6 and are radiated thereby.

Referring now to FIGURE 2 of the accompanying drawings there is illustrated a receiver and associated control circuit for controlling the lights within a building in response to reception of a modulated carrier signal generated by the transmitter of FIGURE 1. The circuit illustrated in FIGURE 2 comprises an antenna 39 feeding an appropriate receiver 41 which may be a superheterodyne receiver, a super-regenerative receiver or other appropriate receiver. The receiver 41 develops an audio output signal at the modulating frequency namely, 115 cycles per second across a primary winding 42 of an audio transformer 43 having a center tapped secondary winding 44. The secondary winding 44 feeds a rectifier circuit which produces a DC. signal, in response to 115 cycles, for controlling the energization of a control relay. The secondary winding 44 includes an upper terminal 46, a center tap terminal 47, and a lower terminal 48 and is tuned to 115 cycles per second by a capacitor 50 connected in parallel therewith. The terminal 46 is connected via a coupling capacitor 49 to ground potential and is further connected via a resistor 51 to an anode 52 of a thyratron 53. The thyratron 53, which constitutes the rectifying element of the circuit, further comprises a screen grid 54 connected to the tap 48 on the secondary winding 44, a control grid 56, and a cathode 57 connected to ground. The control grid 56 is connected via a coupling capacitor 58 to the center tap 47 of the transformer winding 44 and also through a resistor 59 to a lead 61. The lead 6 1 is connected to ground through a filter capacitor 62 and a shunting resistor 63. The lead 61 is also connected to a terminal A of a pair of terminals A and B, terminal B being connected to ground through a second filter capacitor 64. An impedance as will be more fully explained subsequently is connected between the terminals A and B and in conjunction with the filter capacitors 62 and 64 constitutes a filter section for a rectifier power supply. Specifically, the terminal B is connected through a dropping resistor 66 to the anode of a diode 67 having its cathode connected through a dropping resistor 68 to one end of a secondary winding 69 of power transformer 71. The other end of the winding 69 is connected to ground. The cathode of the diode 67 is also connected to the anode of the diode 68 having its cathode connected to ground through a filter circuit comprising a resistor 73 and a filter capacitor 74 connected in series. The transformer 71 further includes a primary winding 76 which is connected across a source of alternating current and which has one end connected via a lead 77 to the terminal 48 of the secondary winding 44 of the audio transformer 43. The transformer 71 also includes a secondary winding 78 which is employed to heat the filament of the tube 53 and further provides power to a light control relay 79 as will be explained more fully subsequently.

Continuing with a description of the circuit, the cathode of the diode 72 is connected via a lead 81 which constitutes the B+ lead of the circuit to one end of a coil 82 of an electromagnet 83 the other end of which is connected to the anode 52 of thyratron 53. The electro-magnet 83 further comprises an armature 84 which when attracted by the coil 82 is adapted to engage a fixed contact 86. The coil 82 is shunted by a holding capacitor 87 for purposes to be explained subsequently. The stationary contact 86 of the electromagnet 83 is connected to one end of the coil 79 of the light control relay generally designated by the reference numeral 8 8, the other end of the coil 79 being connected to the X terminal of the secondary winding 78 of the power transformer 71. The relay 88 further comprises a stationary contact 89 and a movable contact 91 which is adapted to be actuated by the armature of the relay 88 and upon energization of the coil 79 to be moved into engagement with the stationary contact 89. The contacts 89 and 91 are connected in the lighting circuit of the building such that upon the contact 91 engaging the contact 89, the lights within a building are turned on.

In operation the diode 67 and the filter circuit comprising capacitor 64 and the impedance between terminals A and B provide a bias voltage for the control grid 56 of the thyratron 63 so that the tube is normally rendered nonconductive. However, upon the receiver 41 receiving a carrrier frequency modulated by the appropriate audio frequency; namely, 115 cycles, an audio signal appears across the secondary winding 44 of the audio transformer 43. Upon the audio signal instantaneously attaining a polarity such that the terminal 48 of the secondary winding 44 is positive with respect to the terminals 46 and 47, the signal on the grid 54 is sufiicient to overcome the effect of the negative bias on the control grid 56 and therefore the thyratron 53 fires causing the relay 83 to be energized. Upon energization of the relay 83, the movable contact 84 engages the stationary contact 86 and completes a circuit from the terminal X of winding 78 through the coil to ground and therefore the coil 79 is energized. Upon energization of the coil 79 the contact 91 is caused to engage the contact 89 and the light circuit is completed thereby energizing whatever lights are connected in the circuit.

In order that the circuit may be turned on and off from externally of the building, the terminal 48 of the secondary winding 44 of the transformer 43 is connected via the lead 77 to one side of the AC. input line; that is, to one side of the primary winding 76 of the power transformer 71. In consequence of this connection when the terminal of the winding 76 to which the lead 77 is connected swings negative with respect to ground, the anode 52 of the thyratron 53 is driven negative with respect to ground and the tube is rendered non-conductive. Therefore, the circuit automatically de-energizes the tube once during each cycle of the power line voltage. The input signal in the example chosen for purposes of illustration is 115 cycles per" second which is approximately twice the AC. line frequency and therefore the thyra-tron 53 is cut off after every two cycles of the audio signal. However, the holding capacitor 87 which is connected in parallel of the winding 82 of the relay 83 discharges through the coil 82 during the interval when the thyratron 53 is non-conductive so as to maintain the coil energized. Upon discontinuance of reception of the modulating signal; however, the capacitor 87 becomes sufficiently discharged after a few cycles of the power line signal to permit de-energization of the winding 8. 2 and permits release of the movable contact 84 of the relay 83. Upon the contact 84 becoming disengaged from the contact 86, the relay 79 is de-energized and the light circuit is opened.

If a burglar alarm system is not to be employed with the apparatus illustrated in FIGURE 2, a simple resistor or choke may be inserted between the terminals A and B of the control circuit to provide the requisite continuity in the bias circuit of tube 53. However, if a burglar alarm system is to be employed with the inspection system of the invention, a burglar alarm circuit, as illustrated in FIGURE 3 of the accompanying drawings, is connected between the terminals A and B of the FIGURE 2.

Referring now specifically to FIGURE 3 of the accompanying drawings a relay 93 is provided with a movable contact 94, a stationary contact 96, and a relay coil 97. When the coil 97 is energized the contact 94 is held out of engagement with the contact 96. The coil 97 is provided with a terminal 98 and a terminal 99 with the terminal 99 connected to the terminal A of FIG- URE 2. The terminal 98 of the coil 97 is connected via a lead 99 to a terminal 101 of a burglar alarm loop 102. The loop 102 is normally employed in burglar alarm systems in order to detect illegal entry by breaking through or opening a window or door or similar building opening. The loop comprises a wire or other conductive material extending between the fixed and movable member of each opening and extending across the closure member of the building opening so that if illegal entry is efiected -by illegally opening or breaking in through the closure member, the conductor is broken and opens the circuit. The loop 102 terminates in a second terminal 103 which is adapted to be connected via a lead 104 to the terminal B of the circuit illustrated in FIGURE 2. The loop 102 is adapted to be shunted by a key switch 106 so that when the proprietor or other individual of an establishment opens the door in the morning he first closes the key switch 106 so that the loop 102 is shunted and when windows or doors or other aperture closures are opened and break the continuity of the loop 102 the alarm will not go off.

It will be noted that when the circuit illustrated in FIGURE 3 is connected between the terminals A and B of FIGURE 1 so long as the loop 102 is continuous or the switch 106 is closed, a continuous circuit is established between terminals A and B of the circuit of FIGURE 2. The resistance 63 of the bias circuit of FIGURE 2 is chosen in conjunction with the resistances 66 and 68 of the circuit such that the current through the coil 97 of the relay 93 of FIGURE 3 is sufficient to energize the relay. So long as the coil 97 is energized, the movable contact 94 of the relay 93 is maintained out of engagement with the fixed contact 96 of the relay. The movable contact 94 is connected to ground while the fixed contact 96 is connected via a coil 107 of a further relay 108. The end of the coil 107 remote from the contact 9'6 is connected to the terminal X of the secondary winding 78 of the power transformer 71. Therefore, when the contacts 94 and 96 are engaged, the relay 107 is energized and pulls its movable contact 109 into engagement with its fixed contact 111 thereby completing an alarm circuit. With normal bias current flowing through the coil 97 and the contact 94 out of engagement with the contact 96 the relay 107 is de-energized and the alarm circuit is opened.

Upon illegal entry of the premises which results in opening the burglar detector loop 102 two things happen. First of all, the bias circuit of the apparatus of FIGURE 2 is opened, thereby removing the negative bias from the thyratron 53. In consequence, upon a positive swing of the voltage on the lead 77 the anode of the tube 52 is driven positive with respect to the cathode. Since a bias voltage is no longer applied to the control grid 56 of the tube 53, the capacitor 62 being discharged through resistor 63, the thyratron is rendered conductive thereby energizing the light circuit of the building and immediately illuminating the entire or selected portions of the premises. Concurrently, the energization of the relay 93 effects energization of the coil 107 which closes the burglar alarm circuit to summon the police.

It is therefore apparent that the instrument illustrated in FIGURE 3 when employed in conjunction with the instrument of FIGURE 2 converts the light control system to a combined burglar alarm and light control system. The only additional equipment required to so convert the system of FIGURE 2 is two relays, a key switch and a burglar detection loop such as the loop 102 plus the actual alarm circuit to a central police station or other listening posts.

The circuit illustrated in FIGURE 2 may be somewhat modified particularly with regard to the circuit for detecting the 115 volts. In FIGURE 4 those elements which correspond to elements illustrated in FIGURE 2 carry the same reference numerals as in the latter figure. Referring now specifically to FIGURE 4 audio signals are developed across the primary winding 42 of the audio transformer 43 and subsequently appear across the secondary Winding 44 of this transformer. The secondary winding 44 is tuned by the capacitor 50 to the frequency of the modulating signal; namely, 115 cycles per second. The A.C. signals developed across the secondary winding 44 are rectified by a rectifier 112, having an anode 113 connected to the terminal 46 of the winding 44 and having a cathode 114 connected via a lead 116 to the end of the resistor 59' remote from the terminal A of the circuit. The lead 116 is connected to a control grid 117 of a triode 1'18 having a cathode 119 connected to ground and having an anode 121 connected via the relay coil 82 to a source of anode voltage; namely, the lead 81. Again, the coil 82 is shunted by a holding capacitor 87.

In the operation of this circuit, the bias voltage developed at the terminal A maintains the tube 118 nonconductive in the absence of a signal appearing across the primary winding 42 of the audio transformer 43. Upon the appearance of a modulating voltage, it is rectified by the diode 112 and appears on the lead 116. The rectified signal on lead 116 is sufiicient to overcome the bias developed on the grid 117 by the voltage applied to the terminal A of the circuit and therefore, the tube 118 is rendered conductive and energizes the coil 82 which operates the lighting circuit. As in the modification illustrated in FIGURE 2 of the invention, the circuit of FIGURE 3 may be connected in the bias circuit so that the system may operate as a burglar alarm as well as a lighting control circuit. Under the latter circumstances, breaking of the loop 102 removes the bias on the tube and both the grid and cathode are at ground potential and the tube is conductive.

The transmitter illustrated in FIGURE 1 of the ac companying drawings is intended to be mounted in a motor vehicle for utilization by policemen, firemen, or private detective agencies, from externally of the building and often at a relatively great distance therefrom. In accordance with a further feature of the invention, there is provided a small portable transmitter which may be employed by a patrolman while making his rounds on his beat or by a night watchman as he makes his rounds through a plant.

Referring now specifically to FIGURE of the accompanying drawings there is illustrated a schematic wiring diagram of a portable transmitter employing a tetrode 123 having a heated cathode 124, a control grid 1'26, and a screen Igrid 127. The tube 123 operates as an oscillator tube, a modulator tube, and a transmitter tube. In order to carry out its multiple functions, the control grid 126 of the tube is connected to ground through a bias resistor 128 and is connected through series connected coupling capacitors 129 and 131 to one terminal of a carrier frequency control crystal 132. The other terminal of the crystal 132 is connected via a coupling capacitor 133 to the screen grid 127 of the tube 123. The junction of the capacitor 129 and 131 is connected through a series circuit comprising capacitor 134 and neon tube 136 to ground. The junction of the capacitor 134 and 136 is connected through a high resistance 137 to a positive terminal of a battery 138 which supplies the high voltage for the circuit. The positive terminal of the battery 138 is connected through a resistor 139 and RF. choke 140, connected in series, to the screen grid 127 of the tube 123. The positive terminal of battery 138 is also connected through a primary winding 141 of an antenna transformer 142 to an anode of the tube 123. The negative terminal of the battery 138 is connected to a stationary contact 139 of a double pole single throw switch 140. The switch 140 constitutes a first movable contact 141 adapted to engage the stationary contact 139 and a second movable contact 142 adapted to engage a second stationary contact 143. Both of the movable contacts 141 and 142 are connected to ground while the second stationary contact 143 is connected through a filament or an A-cell 144 to the ungrounded end of the filament 124. With the switch 140 in the position illustrated in FIGURE 5 the circuit is de-energized since B+ is not applied between the heated cathode 124 and the anode 125 of the tube 123 and the cathode heater voltage is not applied to the cathode. When the switch 140 is closed B+ is applied to the circuit and the A-cell 144 is connected in a complete series circuit with the filament, producing heating thereof. The primary Winding 141 of the transformer 142 is shunted by the capacitor 143 which is tuned to the frequency of the crystal 132. The transformer 142 further comprises a secondary winding 144 which is 'connected to an antenna 146 of the transmitter.

In operation radio frequency signals developed at the screen grid 127, which is employed as an anode in the oscillator circuit, are coupled through the coupling capacitor 133 and the crystal 132 into the circuit of the control grid 126' of the tube 123. The crystal passes only those signals occuring at its resonant frequency and therefore the oscillation of the oscillator is determined by the resonant frequency of the crystal. The neon tube 136 and the impedance 137 in conjunction with the battery 138 constitute a relaxation oscillator whose oscillations are coupled through the capacitor 134 to the grid 126 of the tube 123. More particularly, the neon tube 136 appears as a capacitor until it breaks down and therefore the voltage across the tube 136 gradually builds up at a rate determined by the value of the resistor 137 and the value of capacity of the tube 136. When the firing voltage of the tube is attained, the tube breaks down and the voltage thereacross falls until the extinction voltage is attained. Thereafter the capacity of the tube is again charged until a breakdown voltage is attained and in consequence the circuit comprises a relaxation oscillator. Both the carrier frequency oscillations and the relaxation oscillations appear at the grid 126 and the tube effects modulation of the carrier by the relaxation oscillator signals. Therefore the carrier and sidebands appear at the antenna 146 and are broadcast therefrom. The frequency of the oscillations produced by the relaxation oscillator are again chosen to be approximately 115 cycles per second so that the portable transmitter of FIGURE 5 may effect control of the same circuits which are controlled by the transmitter of FIG- URE 1. Obviouslly, other audio or superaudio fre quency signals may be employed and the specific frequency mentioned above is exemplary only.

While I have described and illustrated one specific embodiment of my invention, it will be clear that variations of the details of construction which are specifically illustrated and described may be resorted to without departing from the true spirit and scope of the invention as defined in the appended claims.

What is claimed is:

1. A remote control apparatus for a lighting system comprising a transmitter for transmitting carrier signals, a receiver located in a prescribed area remote from said transmitter, said receiver having means for detecting said carrier signal, a burglar alarm system including a continuous conductive loop for protecting building openings, a lighting system for said prescribed area, a switch for controlling said lighting system, and means for actuating said switch, said means being independently responsive to transmission of carrier signals by said transmitter and in response to destruction of the continuity of said conductive loop independently of transmission of said carrier signals by said transmitter.

2. A remote control apparatus for a lighting system comprising a transmitter for transmitting carrier signals, a receiver located in a prescribed area remote from said transmitter, said receiver having means for detecting said carrier signal, a burglar alarm system including a continuous conductive loop for protecting building openings, a lighting system for said prescribed area, a switch for controlling said lighting system, and a single means for actuating said switch, said means being independently responsive to transmission of carrier signals by said transmitter and in response to destruction of the continuity of said conductive loop.

3. A lighting system control comprising a receiver responsive to modulated carrier signals for detecting the carrier modulating signal, a control element having first and second electrodes and at least one control electrode, a bias circuit for said control element, said bias circuit applying a bias voltage to one of said electrodes sufiicient to render said control element non-conductive, said bias circuit rendering said control element conductive upon removal of said bias voltage, means responsive to said modulating signal for applying a voltage to said control electrode to overcome said bias voltage and render said control element conductive, a burglar alarm system, means responsive to energization of said burglar alarm system to remove said bias voltage from said control element, a lighting circuit and means responsive to conduction of said control element to energize said lighting circuit.

4. A lighting system control comprising a receiver responsive to modulated carrier signals for detecting the carrier modulating signal, a control element having first and second electrodes and at least one control electrode, a bias circuit for said control element, said bias circuit applying a bias voltage to one of said electrodes sufiicient to render said control element non-conductive, said bias circuit rendering said control element conductive upon removal of said bias voltage, means responsive to said modulating signal for applying a voltage to said control electrode to overcome said bias voltage and render said control element conductive, a burglar alarm system, including a continuous conductive loop for protecting building openings, said conductive loop being connected in series with said bias circuit, a light circuit and means responsive to conduction of said control element to energize said lighting circuit.

5. A lighting system control comprising a receiver responsive to modulated carrier signals for detecting the carrier modulating signal, a thyratron having an anode, a cathode and two control electrodes, means for applying said detected modulating signal between one of said control electrodes and one of said anode and cathode, a bias circuit for developing a bias voltage on one of said control electrodes sufiicient to render said thyratron nonconductive only in the absence of a modulating signal, a source of alternating voltage, means for coupling said source across said anode and cathode of said thyratron, the voltage of said source having amplitude greater than said modulating signal by the extinction voltage of said thyratron, said bias circuit rendering said control element conductive upon removal of said bias voltage independently of reception of said signals by said receiver, a burglas alarm system having a conductive loop for protecting access openings of an enclosure in which said receiver is situated, said loop being connecteed in series with said bias circuit, a lighting circuit and means responsive to conduction of said thyratron to energize said lighting circuit.

6. A lighting control system, comprising at least one lighting circuit, a switch means for selectively energizing and de-energizing said lighting circuit, said switch means de-energizing said lighting circuit in response to a predetermined voltage being applied thereto, a bias circuit for applying said predetermined voltage to said switch means, first means responsive to a predetermined occurrence for overcoming the voltage of said bias circuit sufficiently to energize said lighting circuit and second means responsive to a further occurrence for opening said bias circuit to energy said lighting circuit independently of said predetermined occurrence.

7. The combination according to claim 6 wherein said switch means comprises an electron tube, said predetermined voltage biasing said tube to non-conduction.

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